JPS60131548A - Developing method - Google Patents

Abstract

PURPOSE:To prevent pulverized carrier particles from attaching to an image bearing member by specifying the magnetization of the magnetic carrier particles of a binary developer to be oscillated with an oscillating electric field. CONSTITUTION:The magnetization of the magnetic carrier of a binary developer to be oscillated with an oscillating electric field is controlled to 15-60emu/g in a magnetic field on a developing sleeve. Accordingly, magnetic bias is lowered by fine pulverization, and carrier particles are prevented from attaching to an image bearing member together with toner particles, and good development processing is executed with finely pulverized carrier particles and toner particles to form an image good in quality.

Description

[Detailed description of the invention] [Industrial applications,].

Regarding the improvement of image development methods for electrostatic latent images or magnetic latent images in electronic and photocopying devices, p.
,,, shi< is 1. A two-component developer containing a mixture of magnetic particles, yellow particles, and toner particles is supplied to the adjuvant transporting carrier surface, and the adjuvant is transported! On the body, 7. ．． Form a developer layer and use the developer layer? The present invention relates to an improvement in a method for developing an electrostatic or magnetic image on a carrier surface.

[Conventional technique, WI].

A method for developing latent images such as military photocopying, copying equipment, etc., and a method for developing a latent image by transporting a developing agent and using a magnetic force on the surface of the carrier. A so-called magnetic brush method is widely used in which toner is deposited on the surface of an image carrier using an electric brush formed by adsorbing, applying, and compressing Jt. Imaging methods are further divided into those using a component developer consisting of magnetic toner particles, and those using a two-component developer consisting of a mixture of magnetic carrier particles and toner particles, or two-component developers. The development method has the advantages that it is relatively easy to control the rubbing of toner particles, that agglomeration of toner particles is less likely to occur, and that magnetic brushes of equal length have good bristles.

To make the toner adhere to the surface of the image carrier from the magnetic brush, there are two methods: a contact method in which the magnetic brush directly rubs the surface of the image carrier, and a contact method in which the magnetic brush surface and the surface of the image carrier are placed close to each other and a vibrating electric field is applied to the developer. There is a non-contact method called the jumping method in which the toner is made to fly toward the image carrier side by means such as vibrating the toner.The latter method has some difficult aspects such as development conditions, but it does not cause sweeping marks on the developed image surface. It has advantages such as being able to repeatedly develop the same screen and being suitable for forming multicolor images.

Conventionally, two-component development methods generally have an average particle size of several tens to hundreds of microns.
A developer is used which is made up of magnetic particles having a diameter of 100 µm and non-magnetic toner particles having an average particle diameter of more than 10 µm, and such a developer has the problem of toner particle silting. Therefore, in order to obtain a high-quality image, this developing method (1. Although many efforts have been made, the reality is that it is still not possible to obtain stable and fully satisfactory images.Therefore, in order to obtain high-quality images, K is a combination of toner particles and carrier particles. It is thought that it is necessary to make the toner particles into finer particles.
If the particles are smaller than μm, the effect of van der Waals force will appear on the Coulomb force during development, and toner particles will adhere to the ground area of the image background, causing so-called fog, which will trap the developer transport carrier. It becomes difficult to prevent fogging even by applying a DC bias voltage to the toner particles, ■ it becomes difficult to control triboelectric charging of toner particles, and agglomeration is likely to occur. The bovine particles also become attached to the electrostatic image area of the image carrier.

The reason for this is considered to be that the force of the magnetic bias decreased and the carrier particles adhered to the image carrier side together with the toner particles.

Note that when the bias voltage becomes large, carrier particles also begin to adhere to the ground portion of the background. The adhesion of such toner particles and carrier particles to the image background area can be tampered to some extent by performing development under the presence of a single vibration electric field, but it has not been possible to completely prevent it. . For this reason, there is a limit to how fine the toner particles and carrier particles can be made, and it has been practically difficult to make them finer.

[Purpose of the invention]

The object of the present invention is to use a developer consisting of finely divided toner particles and carrier particles, and based on the above-mentioned problems (□), there is no deterioration in image quality, and a developing method that can obtain clear images with high reproduction fidelity. Our goal is to provide the following.

[Structure of the invention]

The above purpose is to form a developer layer by supplying a two-component developer mainly consisting of an M-frame carrier element and toner particles onto the surface of a developer transport carrier, and to vibrate the developer layer on the developer transport carrier surface. In the method of developing a latent image on the surface of an image carrier by placing it under an electric field, the magnetic carrier particles have a magnetization of 15 to 60
*Achieved by an electrographic method characterized by mu/I.

1, 1 1 That is, the method according to the present invention uses magnetic 1゛ particles with a magnetic particle size of 15 to ωemu/I as the magnetic particles of the two-component developer, and develops under an oscillating electric field. This makes it possible to use micronized magnetic carrier particles and toner particles without two pulls.

In general, if the average particle size of the magnetic carrier particles is large, the ears of the magnetic brush formed on the Φ developer transport carrier are rough, and the electrostatic image is developed by applying vibrations to the electric field. However, unevenness tends to appear in the toner image,
@ The toner concentration in the ears is low (because of this, problems such as high-density development cannot be performed occur). As a result of experiments, it was found that the effect begins to appear when the average particle size is 5 OIs or less, and in particular, when the particle size is 30- or less, the problem of By making the magnetic carrier into fine particles, the toner concentration in the spike increases, and high-density development is performed, which solves the problem.However, when the carrier particle force exceeds the stiffness of 1,
O may adhere to the surface of the image carrier together with toner particles, or O may become easily scattered.

These phenomena depend on the strength of the magnetic field acting on the carrier particles,
It is also related to the strength of magnetization of carrier particles due to trapping,
Generally, when the average particle size of carrier particles becomes 15 μm or less, a tendency gradually begins to appear, and when the average particle size becomes 5 μm or less, it becomes noticeable. Then, some of the carrier particles adhering to the surface of the image carrier are transferred onto the recording paper along with the residual toner, and the remaining part is removed from the surface of the image carrier along with the residual toner by a cleaning device such as a plate or a phage. However, with conventional carrier particles made only of magnetic material, i, ■ If carrier adhesion as on recording paper occurs,
It is effective to provide recycling 'am.

However, fundamentally, it is most important to minimize the amount of carrier adhesion to the surface of the image carrier. According to various studies conducted by the present inventors, a practically preferable result is obtained when the magnetization of the fruit carrier is 15 to ωemu/I to the magnetic field on the developing sleeve;
It has become clear that especially good results can be obtained when the temperature is u/II.

If the magnetization of the carrier particles is less than 15 emu/IF, the adsorption force of the carrier to the developer transport carrier is insufficient, resulting in insufficient developer transport, and the carrier is separated from the developer transport carrier surface and migrates to the image carrier surface. -1 magnetization exceeds ωemu/9, the formed magnetic brush ears become rough and the image becomes rough, and since the ears are high, breakdown easily occurs through the high ears. (It becomes difficult to apply a high (1 bias voltage), the adsorption force of the carrier to the surface of the developer transporting carrier becomes excessive, the toner particles are strongly compressed between the carrier particles and the developer deteriorates, and the magnet rotates. This developer conveying device is not practical because it causes problems such as carriers being easily scattered.

Further, the particle size of the magnetic carrier has an average particle size of 50 particles or less,
Particularly preferred is one of 1 μm or less.

Such magnetic medium particles are made of metals such as iron, chromium, nickel, cobalt, etc., or compounds or alloys thereof, as in conventional magnetic carrier particles, such as triiron tetroxide, r-oxide, etc. Particles of ferromagnetic substances such as ferric iron, chromium dioxide, manganese oxide, ferrite, manganese-copper alloy, or the surface of these magnetic particles are modified with styrene resin, vinyl resin, ethyl resin, or rosin. Resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, etc.
'rl, coated with a fatty acid wax such as stearic acid, or made into resin or fatty acid sock particles containing dispersed magnetic particles. It is obtained by sorting the grains with a woodcutter.

It is also possible to spheroidize the carrier particles by known methods. The spherical carrier has no directionality of magnetization (the developer layer is formed uniformly, there are no edge parts in the carrier particles, and the electric field does not concentrate on the edge part, so the developer transport carrier has a high magnetic field). It has the advantage that even if a bias voltage is applied, image distortion due to discharge and bias voltage breakdown are unlikely to occur.What does it mean to be able to apply this high bias voltage? This means that when the development is carried out by applying two oscillating bias voltages, the effect of K, which will be described later, can be fully exerted.

As mentioned above, wax can also be used as the carrier particles that produce the above-mentioned effects, but in terms of durability, etc., it is preferable to use resins as mentioned above. □Furthermore, it is preferable that insulating magnetic particles are formed so that the resistivity of the carrier particles is 10°Ω or more, □especially 10°Ω or more.

This resistivity is O'! After tapping in a container with a cross-sectional area of 5"0 cII, a load of 1 Klkv- is applied on the packed particles, and a load of 1 Klkv- is applied between the load and the bottom electrode.
This value is obtained by reading the current value when applying a voltage that generates an electric field of 0.00 V/cm.If this resistivity is low, when a bias voltage is applied to the developer transport carrier, the carrier particles will be charged. When injected, carrier particles tend to adhere to the surface of the image carrier, or breakdown of the bias voltage tends to occur.

To summarize the above, the magnetic carrier particles used in the method of the present invention are spherical so that the ratio of the long axis to the short axis is 3 times or less, and there are no protrusions such as needle-shaped parts or etched parts ( The resistivity is preferably 10 Ω or more, particularly preferably 10 Ω or more. For such magnetic carrier particles, magnetic powder consisting of particles as close to spherical as possible is selected and coated with a resin. Alternatively, it can be produced by dispersing fine magnetic powder in a resin, solidifying it, pulverizing it into spheres, or using a spray drying method.

Next, regarding toner, in general, as the average particle size of toner particles decreases, the amount of charge qualitatively decreases in proportion to the square of the particle size, and the adhesion force such as van der Waals force increases relatively. Therefore, the toner particles are difficult to separate from the carrier particles, and once the toner particles adhere to the non-image area of the image carrier surface, they cannot be easily removed by rubbing with a conventional magnetic brush, resulting in fogging. I'll punish you 5
become. In the conventional magnetic brush development method, such problems became noticeable when the average particle size of toner particles was 10 μm or less. In this regard, the developing method of the present invention includes a developer layer,
This problem is solved by performing development using a so-called magnetic push under an oscillating electric field. That is, the toner particles adhering to the developer layer are easily moved away from the developer layer and transferred to the image area and non-image area on the image carrier surface by the electrically applied vibrations, and are also easily separated from the developer layer. When the surface of the image carrier is rubbed with the developer layer, toner particles attached to the non-image area of the image carrier can be easily removed or moved to the image area, and the developer layer If the thickness is made thinner than the gap between the image carrier surface and the developer transport carrier surface, toner particles with a low charge amount will hardly migrate to the image area or non-image area (and the image carrier Because it does not rub against the body surface! It does not adhere to the image carrier due to frictional charging, and toner particles with particle sizes of several micrometers can now be used. Therefore, electrostatic latent images can be developed faithfully. It is possible to obtain a clear toner image with good reproducibility.Furthermore, the oscillating electric field weakens the bond between the etner particles and the carrier particles, reducing the adhesion of the carrier particles accompanying the toner particles to the image bearing surface. In particular, when the thickness of the developer layer is made thinner than the gap between the image carrier surface and the developer transport carrier surface, toner particles with a large charge amount in the image area and non-image area will be affected by the oscillating electric field. The carrier particles vibrate underneath, and depending on the strength of the electric field, the carrier particles also vibrate!
Since the toner particles are selectively transferred to the decoy image portion of the image carrier surface 8, adhesion of the carrier sheet to the image carrier surface is greatly reduced. The electric field may cause toner particles in the non-image area to reach the non-image area.

Sometimes it doesn't arrive. The same goes for the cow, Yarya.

On the other hand, as the average particle size of the toner becomes larger, the roughness of the image becomes more noticeable as described in 5 above.

Normally, mmc' arranged at a pitch of about 10 lines/I11)
For development with high resolution, toner with an average particle size of about 20/1 m has no practical problem, but if a finely divided toner with an average particle size of 10 μm or less is used, the resolution is significantly improved and the difference in shading, etc. It also provides clear, high-quality images that are faithfully reproduced. For the above reasons, the appropriate condition for the particle size of the toner is that the average particle size is 10 μm or less, preferably 10 μm or less. In addition, in order for the toner particles to follow the electric field, the amount of charge of the toner particles should be greater than 1 to 3 μC/11 (
Preferably 3^3o.

μC/I) is desirable. Particularly when the particle size is small, a high amount of charge is required.

Such toner can be obtained in the same manner as conventional toner. That is, it is possible to use a toner in which spherical or amorphous nonmagnetic or magnetic toner particles in conventional toners are sorted by an average particle size sorting means.

Among these, it is preferable that the toner particles are magnetic particles containing magnetic particles, particularly when the amount of magnetic fine particles is 60 w.
Preferably, it does not exceed t%. When the toner particles contain magnetic particles, the toner particles are influenced by the magnetic force of the magnet included in the developer transport carrier, so that the uniform formation of the magnetic brush is further improved.
The occurrence of fogging is prevented, and furthermore, scattering of toner particles becomes less likely to occur. However, the fi? of the magnetic material contained? If the amount is too large, the magnetic force between the toner particles and the carrier particles becomes too large, making it impossible to obtain a sufficient developing density, and also causing fine magnetic particles to appear on the surface of the toner particles. Frictional charging control becomes difficult, toner particles tend to be damaged, and toner particles tend to aggregate with carrier particles. In particular, when using color toner, the amount of magnetic material must be less than 30 wl.% or clear colors cannot be obtained.

To summarize the above, preferable toners in the developing method of the present invention are resins such as those described for the carrier, and K.
can be made by using fine particles of magnetic material, adding a coloring component such as carbon and, if necessary, a charge control agent, etc., using the same method as a conventionally known toner particle manufacturing method. , particularly preferably particles with a diameter of 10 μm or less. Furthermore, spherical toner brings about favorable results in improved fluidity, developer agitation, and transport charging.

In the developing method of the present invention, a developer in which the above-mentioned spherical carrier particles and toner particles are mixed in the same ratio as in a conventional two-component developer is preferably used, but this also includes the necessary Depending on the conditions, a fluidizing agent for improving the fluidity and sliding of particles, a cleaning agent for cleaning the surface of the image bearing member, etc. are mixed. As the fluidizing agent, floidal silicone, silicone soap, metal soap, nonionic surfactant, etc. can be used, and as the cleaning agent, fatty acid metal salt, organic group-substituted silicone, fluorine, etc. can be used as a surfactant. I can do it.

The above are the conditions for the developer, and next we will describe the conditions for the developer transport carrier which forms a developer layer with such a developer and develops the electrostatic image on the image carrier.

Regarding the developer-carrying carrier, a similar developer-carrying carrier is used in the conventional developing method in which a bias voltage can be applied. 1112 to! A structure in which a rotating magnet body having magnetic poles ['] is provided is preferably used. In such a developer transport carrier, the developer layer formed on the surface of the sleeve undulates and moves in a 51□ manner due to the rotation of the rotary magnet. Even if the developer is constantly supplied and there is some unevenness in the layer thickness of the developer layer on the surface of the sleeve, the effect is sufficient to prevent FIRM from actually occurring due to the undulations mentioned above. covered. It is preferable that the developer transport speed due to the rotation of the J rotating iron stone body is almost the same as the speed of movement of the image carrier, or is faster than that. However, it is not limited to these techniques.

In addition, the thickness of the developer layer formed on the developer transport carrier is
It is preferable that the thickness is such that the adhered developer is sufficiently scraped off by the thickness regulating blade to form a uniform layer.
The distance between the developer transport carrier' and the image carrier is 1°.
~zoco- is preferred.

If the surface gap between the developer transport carrier, the image, and the carrier becomes narrower than several tens of micrometers, it will be difficult to form a magnetic pusher that will uniformly develop the toner particles. If the gap is 2000 mm, stable development will not be possible.
/JTF+, the counter electrode effect decreases and sufficient development density cannot be obtained. In this way, if the distance between the developing agent transport carrier and the image carrier becomes extreme (111t6), the thickness of the adjuvant layer on the developer transport carrier cannot be adjusted to an appropriate thickness. When the open chain is in the range of several tens of am to 2000 μm, the developer layer can be formed with an appropriate thickness.Therefore, the RIll and the thickness of the developer layer are determined under conditions where no oscillating electric field is applied. It is particularly preferable to set the condition so that the ear of the magnetic brush does not come into contact with the surface of the image carrier, and is as close as possible to the surface of the image carrier. This is because fogging is prevented from occurring.

Further, the development under an oscillating electric field is preferably carried out by applying an oscillating bias voltage to the three recesses of the developer transport carrier. Further, it is preferable to use a bias voltage that is a combination of a direct current voltage that prevents toner particles from adhering to non-image areas and an alternating current voltage that makes it easier for the toner particles to separate from the carrier particles. However, the present invention is not limited to the method of applying an oscillating voltage to the sleeve or the method of applying a superimposed voltage of DC and AC.

The developing method of the present invention as described above is shown in FIGS.
This is implemented by a device such as that illustrated in the figure.

In FIGS. 1 to 3, reference numeral 1 rotates in the direction of the arrow, and an electrostatic image is formed on the surface by a charging exposure device (not shown). a drum-shaped image carrier made of a photoreceptor, 2
3 is a sleeve made of a non-magnetic material made of aluminum, and 3 is a magnet body that is provided inside the sleeve 2 and has a plurality of N, 8 magnetic poles on its surface in the circumferential direction.
and constitute a developer transport carrier. The sleeve 2 and the magnet body 3 can rotate relative to each other, and the figure shows the sleeve 2 and the magnet body 3.
indicates that it rotates in the direction of the arrow. Further, the N and 8 magnetic poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 1500 Gauss, and the magnetic force forms a developer layer, that is, a magnetic brush, as described above on the surface of the sleeve 2. do. 4 is a regulating blade made of magnetic or non-magnetic material that regulates the height and amount of the magnetic brush; 5 is a cleaning blade that removes the magnetic brush that has passed through the developing area A from above the sleeve 2; Since the surface of the sleeve 2 comes into contact with the developer reservoir in the developer reservoir 6, the developer reservoir is thereby supplied.
This is a stirring screen that stirs the developer mixture to make the components uniform. Since the developer reservoir in the developer reservoir 6 is busy as the toner particles therein are consumed during development, the developer reservoir 8 is used for replenishing the toner particles T as described above.
The hobber 9 is the surface iC [!] that drops the toner particles T into the developer reservoir 6. 1 part. 1o is a bias power supply that applies a bias voltage to the sleeve 2 via the protective resistor 11.

The difference between the devices shown in FIG. 1 and FIG. 3 is that in the device shown in FIG. N'm
In contrast to the fact that the magnetic poles of B have approximately the same degree of 1 east,
In the device K1 shown in Fig. 2, the sleeve 2 rotates in the direction of the arrow, but the magnet body is fixed at 3%. magnetic flux density′
are not the same (the magnetic flux density of the Ni!! pole facing the image carrier 1 is different from the other N).

This is greater than the magnetic flux density of 8 magnetic poles. It should be noted that as the poles facing the image carrier 1, m3 [5KN magnetic poles may be arranged and facing each other as shown, or of course, i#S magnetic poles may be arranged and opposed to each other. By arranging a plurality of magnetic poles to face each other in this way, it is possible to obtain the effect that development is more stable than when a single pole is made to face each other.

In the apparatus described above, the sleeve 2 is set so that the surface gap with the image carrier 1 is in the range of several tens to 2000 μm, and the electrostatic charge and image development of the image carrier 1 is performed. , the magnetic pusher formed on the surface of sleeve 2 = sleeve 2
Alternatively, as the magnetic flux density on the surface of the magnet 3 changes as the magnet 3 rotates, it moves on the sleeve 2 while vibrating, thereby stably and smoothly maintaining the gap between the magnet and the image carrier l. At this time, it imparts a uniform developing effect to the surface of the image carrier 1, resulting in a stable and high toner concentration. In order to prevent fogging and improve the development effect, J-lead
A bias voltage having an alternating current component of 1° 1 oscillation 1" is applied to the 22rcx (7Xt source 10) between the grounded substrate 1m of the image carrier 1. 5, a preferable superimposed voltage of DC voltage and AC voltage is used, the DC component prevents fogging, and the AC component gives vibration to the magnetic brush to improve the developing effect. Note that the DC voltage component usually includes A voltage of 50 to 600 V that is approximately equal to or higher than the valve surface potential is used, and a frequency of 100 B11-10 KHz 1, preferably 1 to 5 KHz is used for the AC voltage component. The waveform is not limited to a sine wave, but may be a rectangular wave or a triangular wave. Note that if the toner particles contain a magnetic material, the DC voltage component may be lower than the valve surface potential. If the frequency is too low, the effect of vibration cannot be obtained, and if it is too high, the developer will not be able to follow the vibrations of the electric field, resulting in a decrease in developer density and the inability to obtain clear, high-quality images. Also, although the voltage value of the AC voltage component is also related to the frequency, the higher the voltage value, the more effective it will be in vibrating the magnetic brush. This also makes dielectric breakdown, such as the phenomenon described above, more likely to occur.

However, the carrier particles in the developer are insulated and spherical with resin etc., which prevents dielectric breakdown.
The occurrence of fogging can also be prevented by using the DC voltage component; however, the surface of the sleeve 2 to which this AC voltage is applied may be coated with an insulating or semi-insulating coating with a resin or oxide film.

As described above, FIGS. 1 to 3 show an example in which an oscillating bias voltage is applied to the developer transport carrier, but the developing method of the present invention is not limited thereto. For example, the development method of the developer transport carrier and the image carrier The developing effect can also be improved by applying vibration to the magnetic brush by extending several electrode wires around the area and applying an oscillating voltage to them. In that case as well, a direct current bias voltage may be applied to the developer transport carrier, or oscillating voltages of different frequencies may be applied. Furthermore, the method of the present invention can be similarly applied to reversal development and the like. In that case, the DC voltage component is set to a voltage approximately equal to the reception potential in the non-image background portion of the image carrier. Furthermore, the method of the present invention can be similarly applied to the development of a photoreceptor having a recording layer and the development of a magnetic latent film. In addition, the applicant of the present application previously filed a patent application in 1984-184 to form a color image by repeatedly developing an image carrier and overlapping a plurality of toners.
No. 381, No. 58-183152, No. 58-1870
It is also possible to apply the method described in No. 00 and No. 58-187001.

This will be explained in detail below using examples.

Example 1 A solution of methyl ethyl ketone 10001R1IC#g dissolved in styrene-acrylic resin 40.9' was spray applied to fine spherical γ-hematite particles 1 at 9 VC using a fluidization head set at a temperature of ■''CK. At t7, resin coating was performed, and further classification was performed using air classification i to obtain a carrier sample (2) with an average particle size of (9) μm.

Further, spherical ferrite grains were treated in the same manner as described above to obtain a carrier sample (2) having an average particle diameter of (9) μm.

When the magnetization of each sample was measured under 900 Gauss, which corresponds to the magnetic field on the sleeve, sample I had 50 emu/I, and sample 2 had (capital).mu/I. Moreover, the resistivity of each sample was all 30'' Dcm □ or more.

Styrene-acrylic resin (Sanyo Kasei High V) toner
-up 110)' 100 parts by weight, carbon black (Mitsubishi Kasei MA-100> 10 parts by weight, and 5 parts by weight of Nib 99) Non-magnetic particles obtained by a pulverization granulation method with an average particle size of 10 μm mixed with the carrier sample I or (2) to prepare a developer, m1
A copying machine equipped with the developing device shown in the figure was loaded and a continuous copying experiment was conducted on a large number of sheets.

- In this case, the image carrier 1 is an amorphous silicon photoreceptor, its peripheral speed is 180 sni/sec, the highest potential of the electrostatic image formed on the image carrier 1 is -500 V, and the lowest potential is 100 V.
■, The outer diameter of sleeve 2 is 30 mm, and its rotation speed is 10 Orpm.
, the magnetic flux density of the N, 8 magnetic poles of the magnet body 3 is 900 Gauss, its rotation speed is 1000 rpm, the thickness of the developer layer in the development area A is 0.6 m, and the distance between the sleeve 2 and the image carrier L is 11i.
The bias voltage applied to the sleeve 2 was 500 V with a DC voltage component of -250 V and an AC voltage component of 1.5 KHz. That is, in this case, the developer layer is brought into contact with the surface of the image carrier 1 as shown in FIG.

Development was carried out under conditions such that the ratio of toner particles in the developer reservoir 6 to the carrier particles was 10 wt %. The average charge amount of the toner was 15μc7g.The test chart was copied as a subject, developed under the above conditions, transferred to plain paper using a corona discharge transfer device, and heated using a heated roller with a surface temperature of 140℃. A copy was obtained by fixing it through a fixing device, and the image quality was visually evaluated.

When a carrier sample (2) with a magnetization of 50 emu/JJ, which is suitable for the method of the present invention, is used, the image on the recording paper shows slight carrier adhesion, but there is no edge effect or capri, and the image is extremely clear with high density. Subsequently, 50,000 sheets of recording paper were obtained, and images remained stable and unchanged from beginning to end.

On the other hand, when Sample (2) with excessive magnetization was used as a carrier, the carrier was scattered and roughness was observed in the image.

Example 2 Parts by weight of finely powdered 7-elite and styrene-acrylic resin were premixed in a ball mill, and then thoroughly melted and kneaded using an extruder. The kneaded material is cooled, pulverized with a jet pulverizer, and further heated to approximately 300°C with a spray dryer.
A dispersed carrier sample with an average particle size of Iμ was obtained by processing it in hot air to make it spherical and classifying it with an air classifier. 18 parts by weight of ELITE and 82 parts by weight of styrene-acrylic resin were pressed in the same manner as in the case of sample (1) to obtain carrier sample (2). When the magnetization of both samples was measured under 1200 Gauss, which corresponds to the magnetic field on the sleeve, sample ■ had a value of 3.
The 0 smu s specimen was loamu/g. Further, the resistivity of both samples was 10Ωa or more. A toner having almost the same composition as that used in Example 1 and an average particle size of 51rrIL was used, and mixed with the carrier sample (1) or (2) to form a developer. I! l! Embodiment 11C is equipped with the developing device shown in FIG.
A copying machine having the same configuration as the one used was loaded and a continuous copying test was conducted on a large number of sheets.

In this case, the conditions of the image carrier are the same as in Example 1, and the outer diameter of the sleeve 2 is also 30 snw, but the rotation speed is 150 r.
pm, the magnetic flux density of the magnetic pole facing the development area A of the magnet body 3 is 1200 Gauss, the thickness of the developer layer is 0.5 inch, the distance between the sleeve 2 and the image carrier 1 is 110.7 m, or 700 A.
m.

The bias voltage applied to sleeve 2 is DC voltage component -2
00V, AC voltage component 2 KH7,1000V.

In this embodiment, the developer layer on the step 2 is
not in contact with the surface. The toner particle ratio of the developer in the developing section 6 is 20 w 4% to the carrier particles.
The image was developed under the following conditions. The average charge amount of toner is μ
C/g.

The transfer and fixing of the development were performed under the same conditions as in Example 1.

When using the method of the present invention as a carrier, the sample (2) having a magnetization of 3Damu/1, the image on the recording paper obtained was very clear with no edge effect or fog, and had a high density. Although we obtained 50,000 sheets of recording paper, we were able to obtain a stable and unchanging image from beginning to end.

On the other hand, when sample (2) with low magnetization was used, carriers adhered to the image plane, resulting in unfavorable results.

Example 3 A developer prepared using the carrier sample ① or 1v used in Example 2 and toner was loaded into the copying machine used in Example 1, and a copying test was conducted.

However, the development conditions were adjusted so that the developer layer did not come into contact with the surface of the image carrier.

The conditions of the image carrier 1 in this case are the same as in Example 1, the outer diameter of the sleeve 2 is also 3 On, but the rotation speed is 1100 rpm,
The magnetic flux density of N, 8fiJA is 700 Gauss, its rotation speed is 500 rpm, the thickness of the developer layer is 0.11 m, and the distance between sleeve 2 and image carrier 1 is 0.7 m, or 700 μ.
m, The bias voltage applied to the sleeve 2 is a DC voltage component of -200V, an AC voltage component of 21Gb, and 100OV.
And so.

Development was carried out under conditions such that the toner particle ratio in the developer reservoir 6 was 2 owL% relative to the carrier particles. The average charge amount of the toner was μC/11. The conditions for transferring and fixing the obtained toner image to the transfer paper were the same as in Examples 1 and 2. Magnetic flux density on the sleeve in this example 7
The magnetizations of Samples 1 and 2 measured under 0.00 Gauss were 2 Semu/I and 8.mu/I, respectively, and Sample 2 had magnetization suitable for the present invention.

When using the method of the present invention using a developer using a sample (2) having a magnetization of 1cJ, the image on the recording paper obtained was extremely clear with no edge effect or fog, and had a high density. It was superior to the image in terms of higher resolution and higher density.

Subsequently, 50,000 sheets of recording paper were obtained, and images remained stable and unchanged from beginning to end.

On the other hand, in the case of the developer using sample (2) with weak magnetization, however, carriers adhered to both the surface of the carrier and both surfaces of the recorded material, resulting in unfavorable results.

〔Effect of the invention〕

As seen in the examples above, using the method of the invention K
Therefore, it is possible to use fine carriers with an average particle size of µm or less without adhering to the surface of an image carrier or recorded material, and when used in combination with a fine toner with an average particle diameter of µm or less, resolution and sharpness can be improved. It is possible to obtain recorded images without high fog. The effects of the present invention are particularly remarkable in the case of development under conditions where the developer layer and the image carrier do not come into direct contact.

Although only an example of an electrostatic copying machine is given in the above embodiment, the application of the recording apparatus to which the present invention is applied, or the electrostatic image forming method, apparatus, etc. used therein are not limited to this. do not have.

Furthermore, if the toner in the two-component developer has magnetism, it goes without saying that a magnetic latent image can also be visualized under the same developing conditions and pressures.

[Brief explanation of the drawing]

1 to 3 are schematic cross-sectional views of the "f" portion showing examples of developing devices suitable for carrying out the present invention. 1... Image carrier, 2... Sleeve, 3... Magnet body, 4... Regulating blade, 5... Cleaning blade, 6... Developer reservoir, 7... Stirring screw, 8...
... Toner hopper, 9 ... Supply low 2, 10 ... Bias power supply, 11.
...Protection resistance, A...Development area, D...Developer, T
... Toner particles, N, 8 ... Magnetic pole. Agent Kuwahara Yoshimi Figure 1 Figure 2? Procedural amendment document 1982, July 8th 1, Indication of case 1982 Patent J [No. 240065 2, Title of invention □ Name of development method (127) Roku Konishi Photo Industry Co., Ltd. 4, Agent 6, Amendment "Detailed Description of the Invention" column of the subject specification. 7. Contents of the amendment (1) The specification, page 26, line 7 [potential 100VJ is corrected to "potential -100VJ"; (2) the specification, page 26, line 11 [and image carrier] are corrected to [potential 100VJ]; is corrected to "image carrier".

Claims (1)

[Scope of Claims] (1) A two-component developer mainly consisting of toner particles and magnetic carrier particles is supplied onto the surface of a developer transporting carrier to form a developer layer, and a developer layer is formed on the surface of the developer transporting carrier. In the method of developing a latent image on the surface of an image carrier by placing a developer layer under an oscillating electric field, the magnetization of the magnetic carrier particles is 15 to 60 em.
A developing method characterized in that it is u/9. Q) The developing method according to claim 1, wherein the oscillating electric field is formed between the developer transport carrier and the image carrier. , 1. . (3) The thickness of the developer layer on the surface of the developer transport carrier is thinner than the gap between the image carrier surface and the developer transport carrier. The developing method according to claims 1 to 3, wherein the toner particles are knee particles. (5) Temporally varying the magnetic field in a region where the developer is vibrated by an oscillating electric field. , the developing method according to claims 1 to 4.